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Nice PET but garbage screen

T

tezza

Veteran Member
Joined
Oct 1, 2007
Messages
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Location
New Zealand
Hi,

I've taken posession of one of the models which was top of my "must have" list. It's a mint-condition Commodore Pet (3032 model).

08-10-29-pet-unpacked.jpg


I bought it as a faulty unit, but I'm hoping I can probably work through the problems and eventually fix it. The main problem is this..

08-10-29-pet-screen-garbage.jpg


..which I figure might be RAM. But then, I've learnt from the Apple experience that you can never tell with such non-specific symptoms.

One thing that surprised me was just how few of the ICs were socketed (compared to the Apple II)? Given the vintage, I'd expected at least the RAM to be socketed but they are hardwired in, which is going to make things a lot tricker.

Anyway, I started off with a simple 4116 RAM piggy-back trick. Oddly, on the second chip I got a change; the screen turned to all zeros? Even stranger, I couldn't repeat this symptom? When I tried piggybacking the chip again, there was no change to the standard garbage display. Piggybacking on the other chips also made no difference. I never saw those zeros again. Weird! Maybe I just didn't have the legs lined up properly.

So. Never mind. I'm glad I've at last got a Pet and in such good cosmetic condition. The video seems rock-solid without any sway or flicker.

Any comments, hints or advice is welcome.

I'm not going to be doing much in the next two weeks though. I'm off to Cyprus for a conference. The hotel has wireless Internet so I'll probably check into the boards from time to time.

But then again... :)

Tez
 
sweet. One of those are pretty high up on my list as well :) But they are rather bulky aren't they?

Oh by the way. You guys need to check out the bbc series "Look around you". A hilarious comedy with references to old computers :) Most episodes are on youtube

look_around_you.jpg
 
Pontus: The 40 and 80 column PETs recently (?) have become reasonably common in Sweden, down to price levels around 200-600 SEK each depending on condition, location and marketplace. If you are eager to get one, it shouldn't be that hard. In worst case, I may be able to supply you.

Tezza: Good luck with the repair. Unfortunately I think I've used up my last good 3032 motherboard, but may find more. Even if I gave them away, shipping would however cost a little. If you find a particular chip has gone bad, perhaps I can help you although most of those chips are reasonably available elsewhere as well.
 
LOL, I'll have to check that out.

I just put the PET to bed but before I did I tried a few more things. Firstly, following the advice of Druid in the link above, I did the piggy-back RAM thing again, but this time looking for changes in the pattern. There was very SMALL changes in the pattern occasionally (the odd character) but this pattern would often remain, even when the piggybacked chip was then removed! I'm assuming a MAJOR change is the one to look for if more than one chip is non-functioning and you are trying the piggyback method.

One more thing. When I turned it on to work on it again a screen full of zeros came up!?? Switching off and on again it resumed to garbage. I'm starting the zeroed screen is another boot problem, perhaps intermittent.

I had a quick go at removing the CPU. It's wedged in tight. A job for another day I think.

Tez
 
carlsson said:
Tezza: Good luck with the repair. Unfortunately I think I've used up my last good 3032 motherboard, but may find more. Even if I gave them away, shipping would however cost a little. If you find a particular chip has gone bad, perhaps I can help you although most of those chips are reasonably available elsewhere as well.
Click to expand...

Anders, keep me in mind if you do come across a working one. The case and VDU on this unit are in great condition. The PSU seems good too. With all these soldered ICs and not having a working equivalent I can use as a test machine, I'm less confident about fixing this one as I was with the Apples. I'd consider paying a few bucks for a 3032 board, and for the shipping also. It's a lot less from Europe than it is from North American for some reason, even though the former is further away from here.

Tez
 
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European shipping costs vary greatly, at least for continental shipping. Traditionally the UK has been the most expensive, followed by countries such as Italy, possibly Spain and unfortunately Sweden. On the inexpensive end you have Germany and the Netherlands. Not sure if France ranks among the cheap or expensive, it depends who the seller is, so to speak.

Fortunately a motherboard doesn't weigh more than 1-2 kg packaged which doesn't drive up the costs too far. In the mean time, you may come across some kind of service manual that would help you find the fault. I strongly believe the CPU is fine, otherwise probably nothing would display at all and besides I've yet come across any 6502 equipment (computer, disk drive) where the CPU was the fault. More likely RAM or perhaps a small logic chip. How about ROM, if the code is corrupted maybe the boot halts?
 
Tez has a PET!

Tez has a PET!

Tez,
Just have to say that is one fine looking PET you have there! Great on knocking one off the wish list.
For me that PET would definitely be a flagship to my collection. Alas, unless I found one lying along the road somewhere I fear I'll never possess one :(
I've even considered buying a hopeless wreck of one and then trying a restore - but me and IC chips don't seem to get along. Back in the 70's when I was home studying with National Radio Institute taking a Color TV course I worked on many IC projects and although I was decent on theory, I was lame on the practical end. I remember I built this color bar generator thing and I couldn't get it right to save my life. It was full of IC's and that kind of put me off to working with them much. I never finished the course :(
Sorry, I'm getting off course here - but seeing that nifty PET of yours evokes old memories.

Good luck with fixing it and 'bringing it back alive' in 2008!
 
carlsson said:
Pontus: The 40 and 80 column PETs recently (?) have become reasonably common in Sweden, down to price levels around 200-600 SEK each depending on condition, location and marketplace. If you are eager to get one, it shouldn't be that hard. In worst case, I may be able to supply you.
Click to expand...

I've seen some show up on "blocket" and "tradera" and I almost went down to Gothenburg to pick one up. Anyway I have too much stuff going on right now to search for one actively, but should you come across one that you don't want for yourself I'm certainly interested.


"So much by thus has never been due much if a reduced number." - Babelfish mangled quote
Click to expand...

Churchill?
 
I had the same exact problem and 80'sfreak on this board helped me by supplying the chip I needed. We basically switched them out until we found the one with the problem. It was one of the 85xx chips, not the RAM.
Bill
 
Luzur hooked up with a seller outside Stockholm who had a truckload of PETs, and there has been some other PETs in the Stockholm - Uppsala - Västerås region. I sold one refurbished 2001N on Retro Gathering.

(And yes, my signature is Churchill's famous one, translated a few steps too many)
 
yep, he even had a PET 2001, i think he got a decent load of money out of the load as well.

he even gave a working 8032 to me as a "thank you" for helping him. :)
 
hmm? someone i know?
Click to expand...

Maybe, it was an ad on blocket with two Pets and some calculators. Judging from the pictures the owner had some fancy wallpaper :)

carlsson said:
I sold one refurbished 2001N on Retro Gathering.
Click to expand...

I've missed Retro Gathering completely, next time I'll have to go.

Hmm, were getting a bit of topic. Hows it going with the garbage on the screen?
 
Hmm.. I just found a loose 4032 motherboard. I also have a complete 3032. Functionality wise, would the 4000 series board work in the 3000 computer (power connector, keyboard, monitor) just that it comes with Basic V4 instead of V2?

I'll look it up and if it appears safe, swap boards in the weekend. If the 4032 board is fully OK, I may offer Tezza to buy it. While it wouldn't make his PET a genuine 3032 anymore, it would make it work.
 
Hi Andres,

Let me know how it goes. I'd certainly consider it although it would depend on what the all up cost is incl. shipping etc.

My ultimate goal would be authenticity but a working PET would be ok, while I slowly work at the 3032 board to get it going, or perhaps see if I can source another in the long term.

Anyway, I'm packing for Cyprus at the moment and probably won't be on the boards for a few days. I hope to log on from there though.

Tez
 
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